Drier for photographic layer supports in sheet form



April 1969 R. KOEHLER ETAL 3,438,140

DRIER FOR PHOTOGHAPHIC LAYER SUPPORTS IN SHEET FORM Filed July 20, 1966F/GZ FIG]

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ATTORNEY United States Patent U.S. Cl. 34-160 5 Claims ABSTRACT OF THEDISCLOSURE A drying apparatus for photographic sheet material,especially film, of the general type in which the sheet material istransported along a given path by co-operating pairs of guide rollersarranged in spaced parallel relation along such path, the sheet materialbeing guided by the roller pairs being contacted by air streams issuingfrom blower tubes arranged on either side thereof between adjacent pairsof rollers, each of the blower tubes when viewed in cross-section havingflattened side walls extending generally normally to the support path,an inside end wall adjacent said support path which is inclined relativeto said path, and an outside end wall remote from said path extendingbetween the remote ends of said flattened side walls to complete thetube, said inclined inside wall having a slit-like air passage extendinglengthwise therein, whereby a current of air emerging from said passageflows parallel to said inclined wall and upon passing the limit of saidwall generally parallel to the support path. Preferably the remote endwall of each tube is of semicylindrical configuration and the inclinedend wall faces in the direction of movement of the sheet materialthrough the apparatus. The air passage in each tube is preferablylocated at a point in the inclined end wall closer the shorter of thetwo flattened side walls.

This invention relates to a drier for photographic layer supports insheet form, especially sheet film.

Such driers are known with a series of transport rollers arranged onboth sides of the path of the layer support, blower tubes being arrangedbetween the rollers to blow onto the layer support dry air which entersthe tubes from their ends at both sides.

In known arrangements of this type, the blower tubes direct streams ofair extending over the whole width of the layer support substantiallynormal to said layer support. These constructions have the disadvantagethat even if the air streams from two opposed tubes do not preciselycancel each other out as regards their efl ect on the layer support,satisfactory passage of the leading edge of the layer support is notensured. It is often the case that the leading edge of the layer supportbecomes deflected and does not reach the next guide roller in thecorrect position.

The present invention provides a drier for photographic layer supportsin sheet form, especially sheet film, said drier having a succession oftransport rollers for the layer supports, arranged on both sides of thepath of the supports, and between the rollers, in the transportdirection, blower tubes for directing air onto the supports, the saidtubes having a cross section so deviating from the circular, and havingexit apertures for the air so arranged in a tube surface inclined withrespect to the path of the supports, that after exit from said surfacethe air passes along it and, when it becomes clear of said surface,flows in a direction tangential or approximately tangential to the layersupports.

By means of this tangential guiding of the air flow, the possibility ofthe leading edge of the layer support being deflected to any greatextent from its path is practically excluded.

In one embodiment of the invention the blower tubes are of neartrapezium shaped cross section, the parallel sides of the trapeziumbeing arranged perpendicular to the path of the layer supports, the rearside with respect to said path being of cylindrical curvature and theside' facing said path being inclined thereto at an angle in a rangeclose to 45, an exit aperture in the tube being in the latter surface ata point nearer to the shorter than to the longer parallel side. With ablower tube of this type, experiments have shown that the flow of air isparticularly closely tangential to the layer supports.

Preferably the exit aperture in a tube is in the form of a slitextending over a distance corresponding to the relevant dimension of thelargest layer support to be dried in the drier. This construction allowsthe use of a simple manufacturing method, namely the milling of theslit, and ensures a sufliciently even distribution of air over the wholewidth of the layer support.

An arrangement is to be preferred in which in the case of a trapeziumshaped tube cross section, the tubes are arranged with their longerparallel side facing the direction of approach of the layer supports.The tangential flow is then in the opposite direction to the layersupports passing through. A counter flow is thus produced which isparticularly advantageous for drying, and since there is a higherrelative speed of layer support to air stream, lower drying temperaturescan be used than with conventional arrangements, whilst maintaining thesame drying time.

The invention is illustrated by way of example in the accompanyingdrawing, in which:

FIG. 1 is a diagrammatic sectional elevation of a drier according to theinvention, and

FIG. 2 is a cross-section of a blower tube of the drier of FIG. 1.

Referring to FIG. 1 of the drawing, in a fixed airtight housing 1 aresupported a large number of pairs of transport rollers 2, 3 which aredriven by conventional drive, not illustrated, e.g. by way of bevelgears. The rollers are supported in frames 4 which can be inserted intocorresponding recesses 5a in partitions 5 which are normal to the rolleraxis and of which only one is visible in the drawing. In order not todamage the photographic layer, which is extremely sensitive in the dampstate, the rollers are made of butyl rubber, polyethylene, hardenedpaper or the like.

The drier is intended to be fed with the photographic layer supports tobe dried, at an opening 1a in the housing, either by hand orautomatically from a known type of continuous developing device in thecase of sheet film. The sheet film, for example, passes downwards in thedrier. This construction is of advantage, but the drier could be adaptedfor horizontal passage of the sheet film.

In a vertical portion of the drier, constituting a drying chamber,between each pair of rollers and the next pair, a pair of blower tubes6, 7 is arranged, one on each side of the path of the sheets and spacedfrom said path. The shape of the blower tubes and the direction of theair stream therefrom are described below with reference to FIG. 2 of thedrawing.

The blower tubes 6, 7 are mounted in the partitions 5. One partition 5is part of an air supply channel of large cross-section, into which airis blown by a blower 8 through a pipe 9. The blower 8 i mounted in ahousing 10 which is attached to the housing 1. Between the housing 1 andthe housing 10 there is an air passage 11, through which air can beaspirated from the drying chamber by the blower 8. In addition, thechamber 10 also has an opening 10a, so that fresh air can also beaspirated into it. From the pipe 9, a further pipe 12 branches off,which leads a proportion of the air conveyed by the blower 8 to theexterior. The drier is therefore an air circulating drier to which acertain proportion of fresh air is fed and from which a correspondingquantity of moist air is discharged.

Laterally of the rollers 2, 3 and the blower tubes 6, 7 a perforatedpartition 13 is arranged which provides a separate suction channel inthe housing 1. Air which has emerged from the blower tubes 6, 7, aftercontact with the film sheet, passes through holes in the partition 13into the suction channel and through the passage 11 to the blower 8. Aheater is preferably provided in the entry to the housing 10.

Beneath the lowest pair of rollers 2', 3 is arranged a slot 14 in thebase of the housing 1, through which slot completely dried film sheetscan fall into a receiver 15. This is accessible through an opening 16 ina front wall of the houing 1, so that the film sheets can be removed atthat point.

Referring now to FIG. 2, a blower tube is seen to have a cross-sectionof near trapezium shape, the parallel sides 6a, 6b of which,perpendicular to the path of the layer supports, are approximately twiceas long as the smaller transverse dimension of the tube. One narrow side60! is inclined at about 45 with respect to the parallel surfaces andthe other 60 is of cylindrical curvature. Resulting from themanufacturing method (extrusion), and to be preferred for improvedguiding of the film sheets, all corners are rounded, particularly at thepoints facing towards the film sheet path. The blower tubes arepreferably made of aluminium, which can easily be given the requiredshape by the extrusion method.

In the said inclined surface 6d, at a point nearer to the shorter thanto the longer parallel side, there is milled an exit slit 6e.Experiments have shown that with this type of cross-section when thereis excess pressure within the tube a stream of air is produced which, asshown by the arrow in FIG. 2, on emergence first flows in a directiontangential to the inclined surface 6d and when clear of the tube surfacemoves in a plane normal to the two parallel surfaces 6a, 6b, i.e.tangential or approximately tangential to the path of the film sheets.

The transport rollers need not be arranged opposite each other in pairsas shown, but alternately on the two sides of the path of the filmsheet, A blower tube can then be arranged opposite a transport roller ineach case. The blower tubes can, instead, be positioned to direct theair stream in the direction of travel of the film sheet, so that dryingtakes place with the air flow and the film sheet moving in the samedirection. This arrangement has a rather poorer drying eflect comparedwith the counterflow method, but results in better guiding of theleading edge of the film sheet.

Furthermore, there may be used drier tubes of similar cross-section inwhich an air flow emerging from apertures is directed along a surfacewhich is inclined at an angle of less than 60 to the direction of theoutlet aperture and then is deflected into a more or less tangentialdirection to the articles being dried.

We claim:

1. Drier for photographic layer supports in sheet form, especially sheetfilm, comprising a series of rollers for transporting said supportsalong a predetermined path, said rollers being arranged in spacedparallel relation along both sides of said path; and a series of blowertubes for directing air upon said supports, said tubes being disposed inspaced parallel relation to said rollers, one between each adjacent pairof such rollers; each of said tubes when viewed in cross-section havingflattened side walls extending generally normally to the support path,an inside end wall adjacent said support path which is inclined relativeto said path, and an outside end wall remote from said path extendingbetween the remote ends of said flattened side walls to complete thetube, said inclined inside wall having a slit-like air passage extendinglengthwise therein the axis of the passage being at an acute angle tosaid outer surface of said inclined wall whereby a current of airemerging from said passage flows parallel to said inclined wall and uponpassing the limit of said wall generally parallel to the support path.

2. Drier according to claim 1, wherein the blower tubes are of generallytrapezoid shaped cross section with the two parallel sides of thetrapezoid being arranged perpendicular to the path of the layersupports, the side between said parallel sides remote from said pathbeing of approximately cylindrical curvature and the side bet-ween saidparallel sides adjacent said path being inclined thereto; said airpassage being in the latter side at a point nearer to the shorter of thetwo parallel sides.

3. Drier according to claim 2, wherein said side adjacent said path isinclined thereto at an angle in a range close to 45.

4. Drier according to claim 1, wherein said slit-like air passageextends at least over a distance equal to the corresponding dimension ofthe largest layer support to be dried in the drier.

5. Drier according to claim 1, wherein said inclined wall is inclinedoutwardly and forwardly with respect to the path of the supports.

References Cited UNITED STATES PATENTS 2,229,921 1/1941 Golf et a1.34-23 XR 3,147,090 9/1964 Russell et al 34-160 3,316,657 5/1967 Haywood341 16 XR FOREIGN PATENTS 218,770 2/ 1910 Germany. 612,366 4/1935Germany.

H FREDERICK L. MATTESON, JR., Primary Examiner.

H. B. RAMEY, Assistant Examiner.

